Continuous molding of fastener products and the like and products produced thereby

ABSTRACT

Improvements for an apparatus for continuously molding small fastener elements integral with a base web from a flowable resin. The apparatus includes a rotating cylindrical mold roll defining small fastener element-shaped mold cavities in its peripheral surface. Resin is forced into the cavities under pressure at a gap between the mold roll and either a pressure roll, a pressure nozzle, or a belt. The improvements compensate for the crowning of the mold roll under high molding pressures, enabling the molding of wider products. Other gap controls include skewing, product thickness feedback, and active roll bending. Some pressure and backup rolls have compliant surfaces for conforming to the mold roll to avoid high contact loads that can damage the cavities.

BACKGROUND OF THE INVENTION

This invention relates to improved equipment and methods for makingcontinuous fastener products and the like, and to products produced bythe equipment and methods.

Fastener products, such as hook components of hook-and-loop fasteners,are manufactured by a continuous molding method employing a cylindricalmold roll which has fastener-shaped cavities formed in its periphery.Often the mold roll is formed of an axially compressed stack ofring-form mold plates. In operation, molten polymer from an extruder isintroduced into a pressure zone in which the molten polymer is forcedunder high pressure into the fastener cavities of the cooled mold roll,to form fastener elements (e.g. hooks) integrally molded with a baselayer. In some cases the pressure zone is a nip formed by a mold rolland an adjacent pressure roll. In other configurations the pressure zoneis formed between a conforming stationary pressure head and a mold roll.Typically, the smaller the fastener elements (or the like), the fasterthe optimal production speed. The more viscous the resin, or the lowerthe temperature of the cooled roll, the higher must be the pressureachieved in the pressure zone in order to make a satisfactory product.Typically, mold rolls of about 10 inch diameter and 12 inches in axiallength have been employed.

SUMMARY OF THE INVENTION

We have realized that many advantages can be obtained by employinglonger mold rolls and correspondingly wide pressure zones to form wideproducts, while providing means to accommodate effects of thedistribution of pressure along the length of the mold roll. By thismeans, products molded with wide widths can have uniform productthickness and other properties previously found only in narrowermaterials.

We also have realized that many advantages can be obtained by raisingthe pressure in the pressure zone, with a conventional roll or a longerroll, to form products having finer features while providing means toaccommodate effects of the distribution of pressure along the length ofthe mold roll.

We have realized that, because of the construction of the molding regionof the mold roll as a stacked series of rings or plates about a centralshaft, the mold roll has limited bending resistance. As a result, if themolding region of the mold roll is made long to produce a wide product,or if the pressure of the resin is increased, the tendency of the moldroll to bend away from the pressure zone under the extreme moldingpressure can cause small separations between adjacent mold plates andundesirable base layer thickness variation across the width of theproduct (i.e. gap variation along the length of the molding region).Also, we realize that non-uniform geometry of the pressure zone canproduce detrimental nonuniformity in the pressure distribution acrossthe pressure zone, which can lead to incomplete filling of some of themold cavities.

According to one aspect of the invention, improvements are made in anapparatus for continuously molding fastener elements integral with abase web from a flowable resin. The apparatus comprises a cylindricalmold roll rotatable about an axis and defining small fastenerelement-shaped mold cavities in the surface thereof, andpressure-applying means to apply elevated operating pressure to forcethe resin into the cavities at a pressure zone. The pressure-applyingmeans and mold roll define a mold gap therebetween for forming the baseweb. The provided improvements include means to maintain the mold gap ata desired thickness profile across the length of the molding regionunder operating pressure that would otherwise tend to produce gapvariations.

The provided improvements are particularly useful if the molding regionof the mold roll is lengthened to about 12 inches or more or if theoperating pressure is raised to higher levels, such that the mold rollis subject to loads in the range of about 1000 to 1600 pounds per linealinch along the mold roll.

In a preferred configuration, the mold roll comprises an axiallyarranged stack of a large multiplicity of disks, at least many of whichhave mold cavities at their peripheral surfaces.

In certain advantageous embodiments, the means to maintain the mold gapcomprises a moving support member on the side of the mold roll generallyopposite the pressure-applying means. The support member is disposed toengage the peripheral surface of the mold roll with sufficient force toresist radial deflection of the mold roll. Preferably a support membercontroller is provided to vary the amount of engagement between the moldroll and the support member in response to operating conditions.

In certain embodiments, the apparatus includes a sensor to provideoperating condition information to a support member controller. In somecases the sensor is constructed to detect the presence of molded resinon the peripheral surface of the mold roll and the controller isconstructed to disengage the support member from the peripheral surfaceof the mold roll when resin is not present. In certain arrangements, thesensor is constructed to respond to a condition of the apparatus that isrelated to the pressure in the pressure zone.

In some preferred embodiments of the invention the depth of the moldcavities from the surface is between about 0.004 and 0.035 inches,preferably between about 0.005 and 0.020 inches, and more preferablybetween about 0.006 and 0.012 inches.

Broadly, the invention relates to completed fastener elements and tocomponents or preforms that form a part of, or are modified to form, acompleted fastener. The term "fastener element" as used herein isintended to include all of these forms.

In some embodiments, however, the mold cavities preferably define theshape of functional fastener elements. In some preferred arrangementsthe mold cavities at least partially define the shape of loop orfiber-engaging hook elements, each element having a pedestal or stemportion and at least one head portion that projects to a side of thepedestal or stem portion. In other arrangements, the fastener elementsare of mushroom shape or of stem-shaped preforms that are subsequentlyprocessed to form mushrooms or other elements having flat or roundedheads.

In some particularly useful embodiments, the support member that engagesthe mold roll has a peripheral surface that is resiliently deformable toconform, in the vicinity of its engagement with the mold roll, generallyto the peripheral surface of the mold roll. In some of these instances,the portion of the support member that directly contacts the surface ofthe mold roll is of a resilient substance, preferably an elastomericmaterial.

In some preferred embodiments the support member comprises a generallycylindrical roll arranged to rotate about an axis of rotation, while insome other embodiments the support member comprises a belt supported toengage the mold roll with substantial pressure.

In some embodiments the means to maintain the mold gap comprisesadjustable structure to elastically deform the shape of thepressure-applying means, to conform to axial deflection of the moldroll. In some cases, the pressure-applying means comprises a pressureroll, the mold gap comprises a nip between the mold roll and pressureroll, and the means to elastically deform the shape is constructed tobend the axis of the pressure roll to maintain the mold gap. In someother cases, the pressure-applying means comprises a nozzle assembly forintroducing the resin to the pressure zone under pressure, the mold gapcomprises a gap between this nozzle assembly and the mold roll, and themeans to elastically deform the shape is constructed to bend the nozzleassembly along the length of the mold gap to maintain the mold gap.

In some preferred embodiments the pressure-applying means comprises apressure roll rotatable about an axis and positioned to form a nip withthe mold roll to provide the mold gap. The means to maintain the moldgap includes a controller to vary the angle between the axes of thepressure and mold rolls to introduce skew to compensate for mold rolldeflection under operating pressure.

In various arrangements according to the invention, means are providedto extract heat from the surface of the support member to cool thesupport member, thus to withdraw heat from the molding process.

According to another aspect of the invention, an apparatus is providedfor continuously molding two streams of fastener product from flowableresin, each product comprising a base web with integral fastenerelements. The apparatus has a cylindrical mold roll rotatable about anaxis and defining small fastener element-shaped mold cavities in itssurface in a molding region. The apparatus also has first and secondpressure-applying means to apply operating pressure to force the resininto the cavities of the mold roll at corresponding first and secondpressure zones. The first and second pressure-applying means and themold roll define corresponding first and second mold gaps therebetweenfor forming the base webs in the molding region. First and secondproduct-removing means are included to remove the product from the moldroll. The first and second pressure-applying means are advantageouslyarranged on generally opposite sides of the mold roll, such that bendingloads applied to the mold roll by the elevated operating pressures ofthe two pressure applying means are substantially balanced. Preferably,the mold roll is of extended length of about 12 inches or more toproduce correspondingly wide webs.

In some embodiments the first and second pressure-applying means eachcomprises a pressure roll and the first and second mold gaps eachcomprises a nip between the mold roll and a corresponding pressure roll.

In some other embodiments, the first and second pressure-applying meanseach comprises a nozzle and shoe assembly for introducing the resin tothe corresponding pressure zone under pressure and the first and secondmold gaps each comprises a gap between a corresponding nozzle assemblyand the mold roll.

According to another aspect of the invention, an apparatus, forcontinuously molding small fastener elements integral with a base webfrom a flowable resin, has a cylindrical mold roll rotatable about anaxis and defining fastener element-shaped mold cavities at its surfacein a molding region, and pressure-applying means are arranged to applyoperating pressure to force the resin into the cavities at a pressurezone. The pressure-applying means and mold roll define a mold gaptherebetween for forming the base web in the molding region. Theapparatus includes a roll arranged to engage the mold roll withsubstantial force, and which has a resiliently deformable surface toconform, in the vicinity of its engagement with the mold roll, generallyto the peripheral surface of the mold roll along the molding region.

In some embodiments, the molding region of the mold roll is of about 12inches or more in length and the resiliently deformable roll comprises apressure roll positioned to form a wide nip with the mold roll toprovide the mold gap, to form a correspondingly wide web. In these andother embodiments, preferably a substantially elevated pressure ismaintained in the pressure zone to produce a load of between about 1000and 1600 pounds per lineal inch against the mold roll in the moldingregion.

In some embodiments, the resiliently deformable roll comprises a supportroll disposed to engage the mold roll on the side generally opposite thepressure-applying means to resist deflection of the mold roll.

In some embodiments useful for producing a laminated fastener productcomprising a molded web and a backing material, the resilient roll andthe mold roll define therebetween a laminating zone for laminating themolded web to the backing material.

According to another aspect of the invention, an apparatus forcontinuously molding fastener elements integral with a base web from aflowable resin has a cylindrical mold roll rotatable about an axis anddefining fastener element-shaped mold cavities at a surface thereof,pressure-applying means to apply operating pressure to force the resininto the cavities at a pressure zone (the pressure-applying means andmold roll defining a mold gap therebetween for forming the base web),and a belt arranged to engage the mold roll.

In some embodiments the belt is arranged to engage the mold roll on theside generally opposite the pressure-applying means to resist radialdeflection of the mold roll.

In some embodiments the belt and the mold roll define a laminating zonetherebetween for laminating the molded web to a backing material.

In some cases, the belt is constructed to extract heat from the surfacewith which it is engaged.

According to another aspect of the invention, certain other improvementsare provided in an apparatus for continuously molding fastener elementsintegral with a base web. The apparatus has a cylindrical mold rollrotatable about an axis and defining fastener element-shaped moldcavities in the peripheral surface thereof, and a nozzle assembly tointroduce a flowable resin to the cavities. The nozzle assembly isconstructed and arranged to apply operating pressure to force the resininto the cavities at a pressure zone, and the nozzle assembly and moldroll define a mold gap therebetween for forming the base web, theapparatus including means to maintain the mold gap at a desiredthickness profile across the width of the wide web under the operatingpressure if the roll is lengthened or if the operating pressure israised to higher levels such that the mold roll is subject to loads inthe range of about 1000 to 1600 pounds per lineal inch along the moldroll.

In some embodiments the means to maintain the mold gap comprises asupport member disposed to engage the mold roll on the side generallyopposite the nozzle assembly with sufficient force to resist radialdeflection of the mold roll, and a controller constructed to vary theamount of engagement between the support member and the mold roll. Insome cases the support member is resiliently deformable.

In some embodiments the means to maintain the mold gap comprises anactuator to elastically bend the nozzle assembly to conform to radialdeflections of the mold roll to maintain the mold gap, and a controllerconstructed to control the actuator to vary the amount of bending of thenozzle assembly.

According to another aspect of the invention, an apparatus forcontinuously molding fastener elements integral with a base web includesa cylindrical mold roll, preferably of extended length to provide acorrespondingly wide web, and a cylindrical pressure roll. The mold rollis rotatable about an axis and comprises multiple stacked disks havingfastener element-shaped mold cavities in their peripheral surfaces. Thecylindrical pressure roll is arranged to engage the mold roll at a nipto form a mold gap for forming the base web. The pressure roll isconstructed to apply operating pressure to force the resin into thecavities. The apparatus also includes an extrusion die to introduce aflowable resin to the nip, and means to maintain the mold gap at adesired thickness profile across the width of the wide web under theoperating pressure, preferably a substantially elevated pressure.

In some embodiments the means to maintain the mold gap comprises asupport roll arranged to engage the mold roll on the side generallyopposite the nozzle assembly with sufficient force to resist radialdeflection of the mold roll, and a controller constructed to control theamount of engagement between the support roll and the mold roll inresponse to operating conditions.

In some embodiments the means to maintain the mold gap includes acontroller to vary the angle between the axes of the pressure and moldrolls to introduce skew to compensate for mold roll radial deflectionunder operating pressure.

By "radial deflection" as used herein, we mean any lateral deflection ofany portion of the axis of the roll, including bending or bowingdeflections.

According to another aspect of the invention, an apparatus forcontinuously molding fastener elements integral with a base web includesa cylindrical mold hoop rotatable about an axis and having fastenerelement-shaped mold cavities in its peripheral surface. The apparatusalso has at least one driven roll arranged to engage an inner surface ofthe mold hoop to drive the hoop and a pressure-applying means arrangedto apply operating pressure to force the resin into said cavities at apressure zone.

In some embodiments of the apparatus of the invention, thepressure-applying means is constructed to apply first and secondoperating pressures at corresponding first and second said pressurezones at first and second mold gaps, respectively, with the mold roll.In some instances, the pressure-applying means comprises a nozzleassembly for introducing resin to the first pressure zone at the firstoperating pressure, the first mold gap comprising a gap between thenozzle assembly and the mold roll. In some cases, the pressure-applyingmeans also includes a pressure roll, the second mold gap comprising anip between the mold roll and pressure roll.

According to another aspect of the invention, a method of continuouslymolding fastener elements on one broad side of a sheet product oppositeanother broad side having surface features, e.g., raised or indentedportions, is provided. The method comprises providing an apparatus thatincludes a mold roll, resiliently deformable pressure roll, and anextruder die, all as described above, passing a sheet product having thesurface features through the nip with the molten resin such that theresilient surface of the pressure roll conforms in the vicinity of thefeatures to protect the features as they pass through the nip. Themethod also includes forming fastener elements integral with a base webon a broad side of the sheet product.

In some embodiments, an abrasive sheet product having molded fastenerelements on one side and abrasive particles on the other side is formedby the in situ laminating method just described, in which the surfacefeatures comprise abrasive particles.

In some embodiments the surface features comprise a decorative texturesuch as an enclosed pattern or decorative fibers as in grass cloth. Insome embodiments, the sheet product comprises a wall covering covered onits back side with fastener elements.

Various aspects of the invention disclosed here enable cost-effectivecommercialization of molded fastener products of extremely wide widthsand products having many very small fastener elements. In particular,fastener products with very thin base layer thicknesses held to veryclose dimensional tolerances can be produced in a practical manner.According to another aspect of the invention, the contact from loadingsystems that are provided according to the invention in the form of loadrolls or load belts, are advantageously employed to extract heat fromthe back of the base layer of the product, to enable production ofthicker base layers or to produce a product with a given base thicknessat a much higher production speed than has previously been possible.

As will be understood from the foregoing and the remaining descriptionand drawings, various features of the different aspects of the inventionmay be advantageously combined in other embodiments for certainapplications.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a molding system with a conformable load roll according tothe invention.

FIG. 1A shows a molding system similar to FIG. 1 with a non-conformableload roll.

FIG. 2 illustrates the use of twin conformable load rolls.

FIG. 3 shows a molding system with a load belt.

FIGS. 4-6 show various methods of cooling a load roll. (FIGS. 5 and 6employ cooling belts).

FIG. 7 is an enlarged view of the contact zone between the load roll andmold roll of FIG. 1.

FIGS. 7A and 7B illustrate different conformable load rollconstructions.

FIG. 7C is an enlarged diagrammatic view of a thermally conductive,conformable material.

FIG. 8 illustrates the use of a series of adjustable load rolls.

FIG. 9 shows a molding system having two conformable load rolls.

FIG. 10 is an enlarged view of the molding nip between a mold roll and aconformable pressure roll.

FIG. 11 illustrates a construction of the conformable pressure roll ofFIG. 10.

FIGS. 12 and 12A show inducing a curvature in, respectively, a solid andstacked-plate roll.

FIG. 13 illustrates skewing a pressure roll.

FIG. 13A is a bottom view of the skewed rolls, taken from direction13A--13A in FIG. 13.

FIG. 13B illustrates an open-loop control system for skewing a pressureroll.

FIG. 13C illustrates a closed-loop control system for skewing andloading a pressure roll.

FIG. 14 shows a system employing skewing and gross load control.

FIG. 15 illustrates the use of a cooling belt for a molding system.

FIG. 16 shows a twin molding nip arrangement, according to theinvention.

FIGS. 17, 17A and 18 through 21 illustrate methods and systems forforming a laminate product.

FIGS. 22 and 23 illustrate systems employing a pressure head and aconformable loading system.

FIG. 24 shows a system with a pressure head and a cooled, conformableload roll.

FIGS. 25 and 26 show control systems for systems with pressure heads.

FIG. 27 is of a dual pressure head system.

FIGS. 28 and 29 illustrate laminating in a pressure head system.

FIGS. 30A through 30C illustrate cross-sections of fastener products.

FIG. 31 shows an embodiment useful for molding fastener elements on abacking material.

FIG. 32 is an enlarged view of part of the nip of FIG. 31, illustratingan effect of a compliant pressure roll.

FIGS. 33 and 34 illustrate systems employing a pressure roll and apressure head.

FIG. 35 shows a system with a mold hoop.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to the embodiment of FIG. 1, an extruder 4 delivers a wideextrusion of molten polymer 100 into the nip (i.e. into the pressurezone) between an elongated mold roll 1 and a pressure roll 2. Thepolymer is forced into fastener-shaped cavities 102 by the pressure ofthe nip, forming a base layer with integral fastener elements. Thefastener elements are, in some cases, fully-formed elements capable ofsnagging loops as molded. In other cases, the fastener elements arepreform elements that are intended to be subjected to a post-formingoperation to form completed fastener elements. The post-formingoperation, in some cases, forms flat top portions on hook or postpreforms. The fastener elements are very small to engage small loops orfibers on a surface, and typically are arranged on the web base with adensity of 500 to 2,000 fastener elements per square inch.

The fastener product 5 is carried on the chilled mold roll 1 a distancesufficient to solidify the fastener elements before removing theelements from their mold cavities 102. A take-off roll 6 is employed topeel the fastener product 5 from mold roll 1. Typically the nip pressureis controlled by actuators (not shown) that force pressure roll 2against mold roll 1.

A load roll 3, on the side of mold roll 1 opposite to the side of thepressure zone, is arranged to engage mold roll 1 to resist the bendingof mold roll 1 that would otherwise occur due to pressure zone forces.By "engage" we mean that the load roll 3 either directly contacts theload roll surface or resin or other product layer on the surface of theload roll, with a substantial contact force. The force exerted by loadroll 3 against mold roll 1 is controlled by a control system 7. Controlsystem 7 varies the position of the load roll to control the loadapplied to mold roll 1 to result in a more uniform product base layerthickness, and to protect against accidental contact between the moldroll and pressure roll. The load applied by the load roll to mold roll 1is preferably about the same as the load applied against the mold rollby pressure roll 2.

In a preferred embodiment, load roll 3 (a support roll) has a resilientexternal layer of thickness t (shown exaggerated in the figure), such as0.5 inch of urethane elastomer. The compliance of the relatively softexternal layer of load roll 3 results in a relatively wide contact area106 between load roll 3 and mold roll 1 and lower average contactpressures than the pressure in the nip between mold roll 1 and pressureroll 2. It also provides more uniform load distribution along the axisof the roll, compensating for small radial deflections of rolls 1 and 2.The relatively low contact pressure avoids damage to the delicate moldsurface (e.g. coining or fatigue in the region of the mold cavities)that would result from high pressure, direct contact with a hard loadroll. The integration of the component of this contact pressure parallelto the plane of the axes of the mold and pressure rolls 1 and 2 providesa reaction force to balance the bending force applied to mold roll 1 bynip pressure. Load roll 3 is preferably constructed and arranged toprovide a reaction load substantially equal to the bending load from thepressure zone, thereby maintaining the straightness of mold roll 1, andthe uniformity of the gap along the length of the rolls.

Control system 7 responds to the thickness of the base layer of theproduct while on the mold roll, as measured by thickness sensor 13, andadjusts the reaction load applied by load roll 3 accordingly. In analternative embodiment, sensor 13 is replaced by a means to measure thedistance between rolls 1 and 2.

Also shown in FIG. 1, in dashed lines, is an alternative placement forthe take-off roll, shown as take-off roll 6a. In this alternativeembodiment, the product as it cools is carried by mold roll 1 through asecond nip between the mold roll and load roll 3, and is subsequentlypeeled away by take-off roll 6a as fastener product 5a. This alternativeembodiment is especially useful when longer cooling times are desired,as it enables the cooling fastener product to be carried by chilled moldroll 1 for a longer time to conduct more heat from the product. Leavingthe product in the mold cavities during contact with load roll 3 alsocan provide important protection to the mold cavities from damage whenhigh loading pressures are employed, as with rolls having a hard outerlayer. In embodiments where load roll 3 is cooled, e.g. by controlledflow of coolant through its interior, additional heat is advantageouslyextracted from the back side of the product as it passes through thesecond nip. The relatively wide contact area between mold roll 1 andload roll 3 can help to promote this heat transfer.

The machine and process shown in solid lines in FIG. 1 are useful whenmolding delicate products that may tend to be damaged from travellingthrough the second nip, whereas the machine and process shown in dashedlines is useful for more rugged products and for high speed production.

As shown in FIG. 1A, passing the cooling product through the nip betweenmold roll 1 and load roll 3' enables, in another embodiment, the use ofa non-conformable load roll 3'. In this embodiment the presence of theresin in the cavities and between the load roll and the mold rollprovides important protection to the surface of the mold roll and themold cavities. Without the product present in the nip between the moldroll and the load roll, the features of the surface of the mold roll(e.g. mold cavities 102) would be susceptible to damage from highcontact or Hertzian stresses, which can be hundreds of thousands ofpounds per square inch. These high contact stresses can, for instance,deform the mold roll surface plastically such as by coining orflattening the tips of some of the fastener-shaped cavities. Even if themold roll surface is not deformed instantly, the repeated, localizedstress applied to the metal forming the inside of a hook-shaped fastenerfrom such hard surface contact can cause fatigue and fracture, resultingin some of the hooks being deformed and the resulting product having anunattractive appearance.

Further features are provided to avoid applying a substantial load tomold roll 1 by hard load roll 3' of FIG. 1A when there is not sufficientpolymer product in the load roll nip to protect the mold cavities. Inone case, thickness sensor 13 is adapted to detect an interruption inthe flow of product. Control system 7 is adapted to respond by quicklyunloading load roll 3', thereby avoiding direct contact load against abare mold roll.

In FIGS. 1 and 1A the axis of load roll 3 or 3' was substantially in theplane of the axes of mold roll 1 and pressure roll 2, all three axesbeing substantially parallel.

Referring to FIG. 2, another embodiment has two load rolls 3a and 3bthat are generally opposite the pressure zone between mold roll 1 andthe pressure roll, but whose axes are out of the plane of the mold rolland pressure roll. Load rolls 3a and 3b are shown to be preferablyarranged in a symmetric or balanced manner about the plane defined bythe axis of the upper rolls. The axes of load rolls 3a and 3b areparallel with each other and substantially parallel with the axes of theupper rolls. This double load roll arrangement advantageously results inan even larger net contact area against mold roll 1 and even loweraverage contact pressure.

Referring back to FIG. 1, one embodiment of the control system employsmanual adjustment by the operator of the pressure applied by load roll3. At start up, a release paper is passed with the extruded polymerthrough the nip between mold roll 1 and pressure roll 2, the papercovering cavities 102 so that the initial melt from the extruder doesnot enter the cavities. The release paper continues to pass through thenip until the surface of mold roll 1 and cavities 102 reach anappropriate operating temperature and speed. At this point, because ofthe presence of the release paper covering the cavities, the product 5or 5a has no fastener elements. When operating conditions are reached,but before applying substantial pressure from either pressure roll 2 orload roll 3, entry of the release paper into the nip is discontinued,exposing cavities 102 to the molten polymer, which begins to flow intothe cavities to form partial fastener elements. The load betweenpressure roll 2 and mold roll 1 is then increased by moving the pressureroll closer to the mold roll until there is enough pressure developed onthe melt to completely fill cavities 102 under the desired conditions.At this point, fastener product 5 or 5a has useful, fully-formedfastener elements integrally molded with the base layer, although theuniformity of the product is affected by the longitudinal bending ofmold roll 1, resulting in a base layer that is typically thicker in themiddle of the product than on the edges. While measuring the thicknessof the base layer (e.g. by thickness sensor 13), the loads applied bypressure roll 2 and load roll 3 are increased until a desirable productis produced.

In a typical operation the load applied by pressure roll 2 is adjustedto produce the desired average or mean product base thickness, and theload applied by load roll 3 is adjusted to reduce base thicknessvariation across the width of the product.

In such an arrangement the mold roll may be two feet or longer in lengthand the load applied by the pressure rolls may be as much as 1600 poundsor more per lineal inch of mold nip.

In a more complex control system 7, signals from thickness sensor 13 (ormultiple sensors arranged to sense various desired control parameters)are fed into an electronic controller that contains an algorithm thatcontrols the loading forces or roll displacements to produce a desiredproduct. Thickness sensor 13 is, in the presently preferred embodiment,a magnetic reluctance sensor placed, as shown, to detect base layerthickness near the pressure zone. Alternatively, sensor 13 (in the form,e.g., of a beta-gauge) may be placed downstream of the mold apparatus.In some situations it is desirable to use a scanning sensor 13 thattraverses the width of the product and measures variation in basethickness across the width. If load roll 3 has a sufficiently compliantsurface and is adjusted to completely balance the load applied by asufficiently stiff pressure roll 2, a stationary thickness sensor 13measuring the thickness at one point along the width of the product mayprovide sufficient control feedback, due to the pressure nip gapremaining even. If the pressure roll is approximately as flexible as themold roll, more load must be applied by the load roll to compensate forthe bending of the pressure roll to maintain an even nip gap by bowingthe middle of the mold roll toward the bowed pressure roll. The stackedplate structure of the mold roll, however, limits the amount of forcedcurvature that can be tolerated before adjacent plates of the mold rollbegin to separate and cause molding flash. Extreme axial loading of themold roll (e.g. by tie rods) can extend this limit and increase theamount of mold roll curvature that can be tolerated. Furthermore,pressure roll 2 is more readily constructed to be rigid in bending toaddress this condition than is the mold roll.

Referring to FIG. 3, in another embodiment a load belt system 108replaces load roll 3 of FIG. 1 as the means to apply a reaction load tomold roll 1 to balance the load applied by pressure roll 2. Load beltsystem 108 has a load belt 14 and at least two or more rolls 110 totension and support belt 14. Belt system 108 is loaded against mold roll1 effectively in the plane of the axes of the mold and pressure rolls.

An advantage of using a load belt system 108 is that the contact loadagainst mold roll 1 is spread over a very wide contact area to make thecontact pressure low. In addition, by the provision of cooling fluid assuggested by arrow A, effective cooling is achievable. In the case ofthe arrangement shown in dashed lines in FIG. 3, contact with thecooling product occurs over a long length of travel so that even at highspeed there is time to extract heat from the back side of the base layeras it passes between load belt 14 and the mold roll.

FIGS. 4-6 show a number of ways, according to the invention, to cool themolding system. To advantageously remove heat at a constant rate fromeither the product or mold roll 1 by a conformable load roll 3, heat iscontinuously extracted. Due to the relatively low thermal transfercharacteristics of most durable, highly compliant materials (as comparedto metals), in most instances it is preferable to transfer heat directlyfrom the load roll surface rather than transfer it through the outercompliant layer of the load roll to an internal cooling system. Coolingthe load roll also reduces the amount of heat that otherwise has todiffuse through the tooling rings or disks of the mold roll to beextracted by a heat removal means such as circulated water in the coreof the mold roll. This reduces the temperature gradient between thesurface of the mold roll and the cooled core of the mold roll, which, inturn, improves the assemblability of the mold roll and helps to keep themold rings in contact with the central mold roll shaft, in part becausedifferences in thermal expansion of the components of the mold roll arereduced due to reduced temperature gradients.

In FIG. 4, cold air is blown across the surface of the load roll from acold air source 112. In FIG. 5 a moving cooling belt 114 is held incontact with load roll 3. Cooling water (represented by block 116) issprayed against the back side of thermally conductive belt 114, whichtransfers heat from the surface of load roll 3. Belt 14 shields loadroll 3 from the cooling water, helping to keep the product dry.

As shown in FIG. 6, an alternative arrangement is to run cooling belt114 through the load roll nip. In the case where the product remains onmold roll 1 and is peeled off after passing through the load roll nip(i.e. by take-off roll 6a in FIG. 1), belt 114 is passed through theload roll nip along with the cooling product. This arrangement isparticularly useful for rapid cooling of the back side of the baselayer, as cooling belt 114 is held in direct contact with the productthrough the entire contact area of the load roll nip. Belt 114 may inturn be cooled (e.g. by water 116 or air) at some distance from the nip.

Referring to FIGS. 7 and 7A, in the presently preferred embodimentconformable load roll 3 has a stiff, relatively non-conformable core 72(preferably steel), a compliant layer 74 (preferably an elastomer), andan outer sleeve 76 which is formed of an elastically deformable materialwith a hard surface, preferably either hard polymer or metal. In thepresent embodiment, the overall diameter of load roll 3 is about 12inches and compliant layer 74 has a thickness t of about 0.5 inch. Asuitable material for compliant layer 74 is urethane, due to itsstability, its ability to be sized by grinding, and its relatively lowcost. For higher temperatures, silicone rubber is also acceptable. Outersleeve 76 preferably has a smooth exterior and has a high thermalconductivity to remove heat either out of the back side of a productwith a relatively thick base layer or directly out of the mold rollitself. Under some temperature and speed conditions, sleeve 76 may beomitted.

Referring to FIG. 7B, an alternative embodiment of conformable load roll3 is pneumatically inflatable, such as an automobile tire. As in a tire,a steel reinforcement belt 71 is preferably employed to stiffen andextend the life of the load roll.

Referring to FIG. 7C, in other embodiments designed to conduct heatthrough a compliant layer of a roll (e.g. load roll 3 of FIG. 1)particles 80 and 82 of thermally conductive materials are molded intocompliant material 74. Materials such as powdered aluminum, carbon orpowdered copper raise the effective thermal conductivity of a compliantlayer that otherwise consists of polymers having relatively low thermalconductivity. In general, a dense distribution of a mixture ofrod-shaped particles 82 and spherical particles 80 provides a higherthermal conductivity at the same volumetric loading ratio than either ofthe shapes alone. This construction is also useful to form the coolingbelts of FIGS. 5 and 6.

The load roll 3 or 3' (or rolls 3a and 3b) of the preceding figures is(are) configured, in some embodiments, as a series of independentlycontrollable rolls 120 arranged along the length of the mold roll, asshown in FIG. 8. Mounted on separate shafts, load rolls 120a, 120b and120c are loaded independently against mold roll 1 to maintain aconstant, even gap between the mold roll and the pressure roll toproduce an even thickness product. Instead of relying on the passiveconformability of the load roll to maintain gap uniformity, thisembodiment enables active control of gap thickness at distinct pointsalong the width of the product. For instance, the load roll or rolls 120near the middle of the span of the mold roll can be employed to apply ahigher load than the rolls 120 near the edges, if required to optimizeor minimize the curvature of the mold roll. The configuration of FIG. 8is particularly applicable for use with a relatively long mold roll 1 orwhen extremely precise gap control is required. Preferably there is atleast one thickness sensor 13 (FIG. 1) associated with each load roll120.

Referring to FIG. 9, in another embodiment a conformable roll 122, ofsimilar construction to that previously discussed for load roll 3, isarranged to load against the back side of pressure roll 2 opposite moldroll 1. Conformable roll 122 maintains a desirable degree of curvature(or lack thereof) in pressure roll 2 to control the gap at the pressurezone between pressure roll 2 and mold roll 1. The compliance ofconformable roll 122 reduces the chance of surface fatigue damage thatmight be caused by two hard rolls rolling against each other, and alsoallows a slight curvature of pressure roll 2 in some instances wherethat is desired. As shown with respect to load roll 3 in FIG. 8,conformable pressure backup roll 122 can be configured as multiple rolls120.

Referring to FIG. 10, in some embodiments it is desirable to constructpressure roll 2' with some compliance. FIG. 10 illustrates an enlargedcross section of the pressure zone between mold roll 1 (with cavities102) and pressure roll 2', which forces melt 100 into cavities 102 andcounteracts the pressure of forming base layer 124 of the moldedfastener product. High pressures are developed, illustrated by pressuredistribution curve 126, that push melt 100 into cavities 102. At higherproduction speeds the compliance of pressure roll 2' results in a widerpressure zone area, increasing the length of time that a given portionof melt is subjected to elevated molding pressures.

As shown in FIG. 11, pressure roll 2' preferably has a relatively hardand rigid surface layer, such as a metal sleeve 128, covering a softer,more compliant layer 130. Compliant layer 130 in some embodiments is anelastomeric material, and in other embodiments is a fluid underpressure.

In some embodiments it is desirable to actively bend a rotating roll tocreate radial deflection. FIGS. 12 and 12A, for instance, illustrate amethod for applying a controllable bending moment to a roll usingsecondary bearings or supports 132a and 132b. This is useful, forexample, to deform pressure roll 2 to match the curvature of the moldroll. Spherical journal bearings that allow a small degree of angulardeflection of the shaft of the roll are suitable for the outer supportbearings 134a and 134b. Between outer bearings 134a and 134b, secondarysupports 132a and 132b bear against the roll and produce a constantbending moment between the secondary supports. Secondary supports 132aand 132b are, in some cases, large diameter bearings that are nearly thesame diameter as the central portion of the roll. In other cases fluidfilm bearings or other rollers are employed to bear on the surface ofthe roll.

FIG. 12A illustrates this bending technique employed to bend a mold roll1 comprised of stacked plates or rings. This active bending helpsprovide compression between the faces of the tool rings where the meltis formed into fastener elements, squeezing the tool rings together toavoid producing molding flash between them. The molding region L of themold roll is that part of the roll comprised of mold plates with moldingcavities or which otherwise forms the molding surface of the roll.

FIGS. 13 and 13A illustrate another method and system for controllingthe thickness of the molded fastener product base layer when mold roll 1is relatively long and therefore tends to deflect under the pressure ofthe pressure zone. In operation, nip pressure between the two rollstends to cause mold roll 1 to move away from pressure roll 2 in a bowedmanner, causing the nip gap to be greater near the middle of the spanthan near the ends, forming a product base layer that is undesirablythicker at its midspan than at its edges. In order to compensate forthis, the axis of pressure roll 2 is controllably skewed relative to theaxis of mold roll 1, to provide a more uniform nip gap along the moldroll. Controller 90 controls the amount of skew. By proper adjustment ofthe skew angle α over a practical range, the gap can be made essentiallyconstant along the length of the nip despite pressure-induced radialdeflection of the mold roll.

A control method employing an "open" control loop is illustrated in FIG.13B. The control technique is called open-loop because the operator 150sets the skew between the left and right sides of pressure roll 2 basedon a signal from a downstream device 40. In the present configuration,device 40 is a Beta-gauge mass sensing device to sense product baselayer thickness and thickness variation across the web. In operation,operator 150 adjusts left and right skew settings on control panel 42,providing the command signals to servo controller 44 which controls leftand right ball screws 48. Feedback 50 from ball screws 48 to servocontroller 44 informs the servo controller of the current position ofthe ball screws. Thus the actual skew position is closed-loop, PID(Proportional/Integral/Differential) controlled inside the servo loop,but the position set point is adjusted by an operator.

In another embodiment illustrated in FIG. 13C, a system controller 52replaces the operator for closed-loop control of the system. Systemcontroller 52 determines the desired amount of skew to produce aconstant base layer thickness and produces a command signal for the ballscrew servo controller 44. The system controller also sends commandsignals to a hydraulic servo controller 58 that controls the position ofleft and right hydraulic load actuators 152. The hydraulic loadactuators adjust the overall position of pressure roll 2 to provide adesired average base layer thickness with minimal variation from oneedge to the other.

The Beta-gauge 40 is a relatively slow method of measurement. It is ascanning system which travels across the product at about 3 to 4 inchesper second, and in one embodiment is located about 20 seconds downstreamfrom the nip. The thickness feedback is therefore delayed by the timerequired for the product to travel to gauge 40 and by the time requiredfor the scanning operation of the sensor. Any corrections made bycontroller 52 therefore need to be based on average trends to avoidinstabilities caused by immediate real time correction.

Alternatively, the thickness of the base layer of the product can besensed in close proximity to the nip, e.g. by sensor 13. Preferablysensor 13 is a non-contacting sensor (e.g. a reluctance sensor floatingon a gas film bearing on the base layer), but sensing mechanisms heldagainst the back of the product with light pressure are also suitable.

Referring to FIG. 14, a preferred embodiment provides a usefulcombination of control techniques, including skew control, formaintaining constant base layer thickness. Gross (average) thicknesscontrol is provided by a control system 140 controlling the normal loadbetween mold roll 1 and load roll 3. Fine thickness control is providedby control system 142 operating actuators at each end of pressure roll 2(to adjust for left/right unevenness) and the skew of pressure roll 2(to adjust for middle/edge unevenness). Such combinations are usefulwhen skewing alone requires impractically large skew angles. Bycompensating for most variation with gross variation control system 140,skewing is only necessary for fine control for automated trimming ofthickness across the width of the product.

Referring to FIG. 15, a cooling belt 160, similar to the belt 114 shownin FIGS. 5 and 6, is useful in some embodiments to cool and support thefastener product through the continuous molding process. As illustrated,belt 160 is introduced to the nip between mold roll 1 and pressure roll2 along with the melt 100. Belt 160 remains in contact with the coolingproduct as it is carried about the mold roll, helping to draw heat outof the base layer and maintaining continuous pressure against the backside of the product. The belt continues through the second nip, betweenload roll 3 and mold roll 1, and provides additional support for theproduct as it is peeled off of the mold roll by take-off roll 6. Afterpassing through a third nip between load roll 3 and knock-down roll 162,belt 160 is peeled away from product 5.

The embodiment of FIG. 15 is particularly useful for very fastproduction speeds, as the prolonged contact between the product and belt160 helps to cool the base layer, so that the product can be quicklypeeled from the mold, without sufficiently cooling the fastener elementsto the point that they can no longer be easily deformed for removal fromthe mold cavities.

Referring to FIG. 16, in some particularly useful embodiments twocontinuous streams of fastener product are simultaneously manufacturedwith a single mold roll. Mold roll 1 is arranged between pressure rolls2 and 2a, defining two pressure zones. Twin extruders 4 and 4a supplymolten resin to the two pressure zones, and the molded product is peeledaway from mold roll 1 by two take-off rolls 170 and 170a. Arranging theaxes of mold roll 1 and pressure rolls 2 and 2a to lie in substantiallythe same plane balances the nip pressure loads exerted on mold roll 1,greatly reducing the tendency of the mold roll to bend. Any of themethods previously discussed may be employed, if necessary, to reducebending of pressure rolls 2 and 2a or to otherwise maintain the evennessof the pressure zone gaps. Belt systems 108, as illustrated in FIG. 3,are useful in place of hard or compliant pressure rolls.

One of the advantages of having two, balanced pressure zones on the sameroll, as shown in FIG. 16, is that the amount of product producible froma single mold roll can be significantly increased. Another advantage isthat the loads on the mold roll are balanced, enabling less expensivemold roll structures with lower stiffness requirements. Yet anotheradvantage is that it enables the production of wider fastener products(i.e. by allowing the use of longer mold rolls) without compromising theevenness of product base layer thickness or product quality.

Referring to FIG. 17, in some useful embodiments an added material 9 isintroduced to a second nip between mold roll 1 and load roll 3 to form alaminate product 5c with molded fastener elements on one side and addedmaterial 9 on the other. It is advantageous that this is done on themold roll while the fastener elements remain protected from laminatingpressure by remaining in their respective cavities. Preceding thelaminating action the back side of the fastener product is re-softened,if necessary, by a heat source 10 to enhance the adherence of the baselayer to the added material 9 in the second nip. Added material 9 isintroduced with the molded fastener product into the second nip, whichin some embodiments is defined by a compliant load roll 3. Following thelaminating nip, the molded product is carried around a substantial arcof the mold roll and cools to the appropriate temperature to set thebond to the added material. The resulting laminate is removed from themold roll by a take-off roll 6a. By bonding the added material to thefastener product while the latter is still being carried on the moldroll, the laminate is formed with the base layer advantageously in aheat-softened, clean condition, resulting in a sound bond. The freshlymolded base layer provides a very good surface for adhering the addedmaterial to form a laminate. In addition, the product base layer issubstantially supported between fastener elements by the surface of themold roll, allowing higher local laminating pressures to be employedwithout deforming the fastener elements. This arrangement enables thelaminating of fastener products with relatively thick added materialsthat are very difficult to pass through the pressure zone (i.e. betweenmold roll 1 and pressure roll 2) without disrupting the molding process.

The embodiment of FIG. 17A is similar to that of FIG. 17 except that theload roll 3 that provides the nip where lamination is performed is ahard roll instead of a compliant one.

Examples of laminate products that are suitable to being formed in thismanner include carpets and wall coverings. The second nip (laminatingnip) may be maintained at more suitable temperatures and/or pressures toprevent damaging such products that would not reliably withstand passagethrough the molding nip. Furthermore, the conformability of load roll 3helps to protect relatively delicate surface formations (of, e.g., awall covering) from undesirable deformation during laminating.

Referring to FIG. 18, other methods of bonding added material 9 to forma laminate material 11 with a molded fastener product include theapplication of an adhesive with an applicator 12. Suitable methods forapplying the adhesive include spraying it directly on added material 9or the back side of the unlaminated base layer prior to the laminatingnip, coating the side of added material 9 with a film layer of adhesivein a previous process, rolling, doctoring and the like.

FIG. 19 shows a variation to the lamination method employing a belt 172that carries added material 9 into and through the laminating nipbetween load roll 3 and mold roll 1. Belt 172 provides extra support forthe added material on the way into the nip and also can provide eitherheating or cooling, depending upon whether the belt is heated or cooled.In some embodiments the belt surface is metallic and of differentconsistency from the compliant layer on the load roll. This machine andprocess is useful for laminating heavy web materials such as floor matmaterial and the like.

FIG. 20 shows another arrangement useful for forming a laminate product,employing a belt system 108 (as in FIG. 3) to provide laminatingpressure. Belt system 108 conducts a belt 14 in close contact with moldroll 1. Both the belt and its roller system are forced up against themold roll to provide sufficient pressure for lamination. This method ismost advantageous for laminations requiring a long time (i.e. a widecontact area in this embodiment) for proper bonding. Another advantageof employing a belt system to provide lamination pressure is thatmicroscopic scuffing of a compliant roll against a hard surface thatmight damage delicate laminate materials, such as paper or vinyl wallcoverings, is avoided, without the high contact pressures of a hard loadroll. The laminated product is either removed with the belt system or iscarried further about the mold roll and peeled off by a separatetake-off roll 6a. An optional cooling system is illustrated by box 174.

FIG. 21 shows a combination of thickness control and lamination. Askew-controlled pressure roll 2 and controller 176 maintain a constantthickness of molded product base layer. As described in previousembodiments, load roll 3 compensates for the load applied by pressureroll 2, minimizing the bending of the mold roll and thereby minimizingthe amount of pressure roll skew necessary to maintain constant baselayer thickness. In addition, a second load roll 178 bears against loadroll 3, helping to maintain the straightness of load roll 3 and alsoproviding an additional pressure nip through which the laminate istrained for improved bonding.

FIGS. 22-29 illustrate other configurations, equally as useful as thosethus far described, that employ a pressure head 8 fed by an extruder orother source of pressurized molten polymer resin to both introduce themolten resin that will form the molded fastener product and to apply thepressure necessary to force the resin into the fastener-shaped moldcavities. As illustrated by the common reference numbers in thesefigures and earlier figures, other components of the systems that employa pressure head 8 are essentially the same as those employing a pressureroll 2. These additional figures show that the novel features describedwith reference to a system with a pressure roll apply equally as well toa system with the pressure head 8. In this respect, the previousdescriptions of the figures to which FIGS. 22-29 correspond are alsoapplicable to these embodiments. FIG. 22 corresponds to FIG. 1, FIG. 23to FIG. 3, FIG. 24 to FIG. 4, FIG. 27 to FIG. 16, FIG. 28 to FIGS. 17,18 and 19, and FIG. 29 to FIG. 20. From these examples it should beevident that any of the other embodiments heretofore disclosed may beadapted to employ a pressure head.

Pressure head 8 in FIGS. 22-29 comprises an extruder nozzle assembly fedby an extruder (not shown). In nozzle throat 8a a sheet form flow ofpolymer is produced, which is applied to the mold roll 1. Shoe surfaces8b of the nozzle assembly that conform to the curvature of the rollserve to maintain the extruder pressure against the roll and to definethe gap with the mold roll that defines the thickness of the base layerof the product. Pressure head 8 thus forces the polymer into the moldcavities in mold roll 1 and forms a sheet-form film or base layer ofpolymer on the surface of the mold roll. As in the previous embodiments,the polymer is forced into the mold cavities to form fastener elementsor the like under the high pressure of the pressure zone. The pressurezone forces tend to bend the mold roll away from the pressure head andare resisted by the methods described above (with, e.g. a compliant loadroll 3 as in FIG. 22 or a belt system 108 as in FIG. 23) to maintain aneven gap for forming the base layer of the fastener product.

Referring to FIG. 25, an arrangement for controlling the gap betweenmold roll 1 and pressure head 8 actively adjusts the shape and positionof the pressure head relative to the mold roll. This can be done, forinstance, in response to thickness sensor 13. The axis of mold roll 1 issupported on suitable bearings (not shown) in a load frame 60. Anextension 60a of load frame 60 supports a head loading system 180 (e.g.a number of hydraulic cylinders or ball screw actuators arranged alongthe length of the pressure head). Molten polymer resin is supplied by amelt source or extruder 61 to head 8 under pressure. Head loading system180 loads head 8, by shafts 62, against mold roll 1 through a film ofmolten resin, thereby maintaining a controllably constant gap betweenmold roll 1 and head 8 for forming the base layer of the fastenerproduct 5.

For active bending of the pressure head 8 to contour the surface of thepressure head along its length to conform to the surface geometry of thebent mold roll, other means of bending pressure head 8 include a numberof tie bolts between the molding head and frame 60, arranged along thelength of the pressure head, that are axially adjusted either byrotating a threaded member or by controlled thermal expansion (i.e.changing the net length of the tie bolts by changing their temperature).Adjusting the lengths of individual tie bolts induces bending moments inpressure head 8 that causes its curved surface 182 to also bend alongits length to conform to the curvature of the mold roll.

Under some circumstances it is desirable for mold roll 1 to be slightlyelastically bent away from pressure head 8 (or pressure roll 2) bypressure zone forces to increase the axial compression between thestacked mold plates that form the mold roll in the vicinity of the highpressure zone. This can reduce the tendency of the molten resin to formflash between the mold plates. In these instances it is advantageous tohave some intentional bending of the mold roll away from the pressuresource, and to force the pressure mechanism (e.g., pressure head 8 orpressure roll 2) to follow that curvature in order to maintain theuniformity of the gap and of the product. Referring further to FIG. 25,the load system 180, comprised of several loading rods 62 distributedalong the length of the pressure head, forces head 8 toward mold roll 1near its midspan to compensate for the curvature of the mold roll. Rods62 are individually controlled by a control system to locally forcepressure head 8 toward or away from mold roll 1 to maintain the desiredgap. This technique is particularly useful to mold extremely wide widthsof product by compensating for the increased bending of relativelylonger rolls subjected to higher overall mold pressure forces.

In some instances it is desirable not to have a perfectly even gapacross the width of the pressure zone. For instance, in some cases it isdesirable to have the gap slightly smaller toward the edges than in themiddle, for example when there tends to be some leakage of polymermaterial from the edges of the pressure zone.

Referring to FIG. 26, use of a load roll 3 with a pressure head 8 ispresently preferred to avoid extreme mold roll curvature in situationswhere the flatness of the product is critical. Molding the product on abowed mold roll results in a base layer that has a degree of complexcurvature, even after being spooled. In some cases such a curvature isdesirable, but in others it is not. Some preferred embodiments thereforeemploy both pressure head curvature control and a load roll on the sideof the mold roll opposite the pressure head. Controller 182 controls therelative positions of load roll 3 and pressure head 8 with respect tomold roll 1. Displacement transducers 184 and 186 and thickness sensor13 provide feedback. In the embodiment shown, controller 182 controlsforce F₂ which loads frame 188, to which both mold roll 1 and load roll3 are mounted, toward head 8. In addition, controller 182 controls forceF₁ which forces load roll 3 against mold roll 1.

As shown in FIG. 27, a particularly advantageous embodiment employs tworelatively stiff pressure heads 8 supplying molten resin to two pressurezones on opposite sides of a single mold roll 1. This produces twocontinuous streams of product 5 and 5' that are peeled from mold roll 1by take-off rolls 6 and 6', respectively. For the reasons alreadydescribed, extremely wide widths of a thin, even product are thusmoldable, due to the balance of forces acting on relatively long moldroll 1.

FIGS. 30A-30C illustrate some of the web base thickness profiles thatcan be maintained by the apparatus and method of the present invention,shown in cross-section across a portion of the length of the mold roll.In FIG. 30A, fastener product 5 has a base web 200 and multipleupstanding fastener elements 202. Maintaining the thickness of the moldgap that forms base web 200 along its length produces a product 5 with abase web 200 of generally consistent thickness t. In another embodiment,shown in FIG. 30B, tapered regions 204 are provided in the predeterminedprofile of base web 200. In some cases, grooves 206 or otherindentations are formed in base web 200, as shown in FIG. 30C. These andother profiles are advantageously maintained at their predeterminedthicknesses by maintaining the profile of the mold gap as describedabove.

Referring to FIG. 31, in another embodiment a compliant pressure roll 2'is employed to protect surface features on the surface of a sheetmaterial 210 introduced to the molding nip between pressure roll 2' andmold roll 1. These surface features would tend to be damaged by beingpassed through a nip formed by two non-conformable rolls. Hard surfacefeatures can also damage non-conformable roll surfaces. This arrangementis particularly useful, according to the invention, for continuousmolding of fastener elements on one side of a sandpaper product havingsurface features consisting of grains of sand or other abrasiveparticles adhered to one broad surface of the paper. It is also usefulfor molding fastener elements on wide sheets of material having delicatesurface features, such as fibers or embossed features, that could bedamaged by the extreme pressures of the molding nip. Examples of thesetypes of materials include upholstery material with leatherette-grainedsurfaces and grass-paper wall coverings. After molding, the finishedproduct is pulled from the mold cavities of mold roll 1 about a take-offroll 211, which also has a compliant outer surface.

FIG. 32, looking in the direction of the flow of material through themold nip between compliant pressure roll 2' and mold roll 1, illustratesthe deformation of the surface of the pressure roll in the vicinity ofabrasive grains 212 as a sandpaper product 214 is passed through thenip. Abrasive grains 212 are quite small in most commercial sandpapers,which have grades from 30 to over 600 for fine polishing applications.The compliant surface of pressure roll 2', preferably of an elastomericmaterial of 60 to 70 durometer for use with a medium-grit sandpaper,conforms to encapsulate the grains 212 and distribute pressure aroundthe grains. Because there is effectively no surface speed differentialbetween rolls 1 and 2', grains 212 do not abrade the elastomeric surfaceof roll 2'. The resulting abrasive product is "in situ laminated" tofastener elements such as hooks for hook to loop fastening. In otherwords, the forming of the base web integral with fastener elements andthe lamination of the base web and abrasive paper occur simultaneouslyin the nip. The resin of the base web is laminated to the back of thesandpaper to provide a means for fastening the sandpaper to a sandingblock or other sanding device.

Referring to the molding system of FIG. 33, in some cases the system hasboth a pressure head 8' and a pressure roll 2. The pressure head 8'preferably applies sufficient pressure in pressure zone P₁ to partiallyfill the fastener element cavities in mold roll 1 and provide a layer ofresin on the exterior of the mold roll. Pressure roll 2 provides asecond application of pressure against the resin in another pressurezone P₂, with the resin still in a formable condition, to complete thefilling of the cavities in the mold roll and produce a base web witheven thickness. Surface 8b' of pressure head 8' is curved to match thecurvature of the mold roll. For molding systems with two pressure zonesP₁ and P₂, support roll 3 is preferably arranged to counteract the loadsagainst the mold roll from both pressure zones (i.e., the three rolls 1,2 and 3 do not lie in a single plane). By applying the resin directlyagainst the mold roll, temperature variations and edge shrinkage can beminimized while, by subsequently employing the pressure roll, uniformfilling of the mold cavities can be assured under, e.g., high speedconditions.

Referring to FIG. 34, in some instances a pressure head 8" extrudesresin directly onto the surface of a pressure roll 2. The extruded resinenters the nip between pressure roll 2 and mold roll 1 where it isforced under nip pressure to fill the cavities in the mold roll. In thiscase it is not necessary, in most situations, for the pressure head 8"to apply substantial pressure, and therefore the three rolls 1, 2 and 3are preferably coplanar.

Referring to FIG. 35, another molding system employs a mold hoop 220with fastener element cavities formed in its outer surface. The moldhoop is held against pressure roll 2 with a loading roll 222, forming amolding nip and pressure zone between hoop 220 and roll 2. Loading roll222 preferably has a conformable surface, as described above withreference to FIG. 1. Additional rolls 224a and 224b provide additionalsupport for hoop 220, which is driven by rotating rolls 2 and 222. Therelatively large diameter of hoop 220 provides room within the hoop forcooling systems 226 for cooling the hoop. This arrangement isparticularly suitable for molding conditions that require the coolingfastener elements to remain in their cavities for an extended length oftime for sufficient cooling, or to enable relatively fast line speeds. Apressure head 228 is shown supplying molten resin to the nip.Alternatively an extruder 4, as shown in FIG. 1, can be employed. Hoop220 is preferably of metal.

What is claimed is:
 1. In an apparatus for continuously molding an arrayof miniature fastener elements integral with a base web from a flowableresin, the apparatus comprisinga cylindrical mold roll comprising astacked series of plates rotatable about an axis of rotation andtogether defining an array of miniature, fastener element-shaped moldcavities in a peripheral surface of the mold roll, and pressure-applyingmeans to apply operating pressure to force the resin into said cavitiesat a mold gap defined between the pressure-applying means and theperipheral surface of the mold roll, to form said fastener elements, theapparatus characterized in that the apparatus includes a support memberon the side of said mold roll generally opposite said pressure-applyingmeans, said support member arranged to apply a substantial reactionforce to the peripheral surface of the mold roll sufficient to resistradial deflection of said mold roll caused by said operating pressure,under conditions in which the miniature mold cavities in the surface ofthe mold roll are protected against permanent deformation from thereaction force, to maintain said mold gap at a desired thickness profileacross the width of said base web under said operating pressure.
 2. Theapparatus of claim 1 in which a molding region of the gap is longer thanabout 12 inches to produce a correspondingly wide web.
 3. The apparatusof claim 1 in which the pressure-applying means is capable of applyingload to said mold roll in the range of about 1000 to 1600 pounds perlineal inch along said mold roll.
 4. The apparatus of claim 1 in whichsaid pressure-applying means comprises a pressure roll, said mold gapcomprising a nip between said mold roll and pressure roll.
 5. Theapparatus of claim 1 in which said pressure-applying means comprises anozzle assembly for introducing said resin to the pressure zone underpressure, said mold gap comprising a gap between said nozzle assemblyand the mold roll.
 6. The apparatus of claim 1 further comprising meansto extract heat from the surface of the support member to cool thesupport member.
 7. The apparatus of claim 1 further comprising a supportmember controller adapted to vary the force applied to the peripheralsurface of the mold roll by the support member in response to operatingconditions.
 8. The apparatus of claim 7 further comprising a sensoradapted to provide operating condition information to the support membercontroller.
 9. The apparatus of claim 8 in which the sensor isconstructed to detect the presence of molded resin on the peripheralsurface of the mold roll, the controller being constructed to unload thesupport member from the peripheral surface of the mold roll when resinis not present.
 10. The apparatus of claim 8 in which the sensor isconstructed to respond to a condition related to the pressure in thegap.
 11. The apparatus of claim 1 in which the depth of the moldcavities from said peripheral surface is between about 0.004 and 0.035inch.
 12. The apparatus of claim 11 in which the depth of the moldcavities from said peripheral surface is between about 0.005 and 0.020inch.
 13. The apparatus of claim 11 in which the depth of the moldcavities from said peripheral surface is between about 0.006 and 0.012inch.
 14. The apparatus of claim 11 in which the mold cavities definethe shape of hook elements constructed to engage loops.
 15. Theapparatus of claim 1 in which said mold cavities at least partiallydefine the shape of hook elements, each element having a stem portionand at least one head portion that projects to a side of said stemportion.
 16. The apparatus of claim 1 in which the support member has aperipheral surface that is resiliently deformable for conforminggenerally to the peripheral surface of the mold roll.
 17. The apparatusof claim 16 in which the support member is arranged to directly contactthe peripheral surface of the mold roll.
 18. The apparatus of claim 16in which the peripheral surface of the support member is of elastomericmaterial.
 19. The apparatus of claim 16 in which the support membercomprises a generally cylindrical roll arranged to rotate about an axis.20. The apparatus of claim 16 in which the support member comprises abelt supported to apply force to the mold roll.
 21. The apparatus ofclaim 1 in whichthe pressure-applying means comprises a firstpressue-applying means; and in which the support member comprises asecond pressure-applying means, the first and second pressure-applyingmeans adapted to apply elevated operating pressure to force the resininto said cavities at corresponding first and second pressure zones,said first and second pressure-applying means and mold roll definingcorresponding first and second mold gaps therebetween for forming twocorresponding base webs.
 22. The apparatus of claim 21 in which saidfirst and second pressure-applying means each comprises a pressure roll,said first and second mold gaps each comprising a nip between said moldroll and a corresponding said pressure roll.
 23. The apparatus of claim21 in which said first and second pressure-applying means each comprisesa nozzle assembly for introducing said resin to the peripheral surfaceof the mold roll under pressure, said first and second mold gaps eachcomprising a gap between a corresponding said nozzle assembly and themold roll.
 24. The apparatus of claim 1 wherein said pressure-applyingmeans is constructed to apply first and second operating pressures atcorresponding first and second mold gaps, respectively, at theperipheral surface of said mold roll.
 25. The apparatus of claim 24wherein said pressure-applying means comprises a nozzle assembly forintroducing resin to the peripheral surface of the mold roll, said firstmold gap comprising a gap between said nozzle assembly and the moldroll.
 26. The apparatus of claim 25 wherein said pressure-applying meansfurther comprises a pressure roll, said second mold gap comprising a nipbetween said mold roll and said pressure roll.
 27. The apparatus ofclaim 1 in which the force applied to the mold roll by the supportmember is applied through the base web.